Field of Invention
The present invention concerns a carbon scrubber used to treat and filter contaminated exhaust air produced in wastewater treatment and conveyance; and other chemical processes.
Description of Prior Art
Wastewater treatment and conveyance; and other chemical processes result in emission of a wide variety of odorous compounds, such as ammonia, organic sulfides, and volatile organic compounds hereinafter referred to as “VOCs”). Contaminated exhaust air is typically a byproduct emitted from sludge in tanks and wells that are part of a wastewater treatment, conveyance, or chemical process. Said contaminated air has to be treated to capture or reduce odorous compounds or pollutants below human smell recognition threshold levels and reduce VOCs levels before the exhaust is discharged to the atmosphere. Various technologies are currently used to treat said exhaust air, including: combustion; scrubbing with water, caustics, bleach, or other oxidants; filtration through filters; use of medias and micro-organisms; dilution with fresh air; and dispersion.
A common system for treating exhaust is a carbon scrubber that directs the exhaust air into the base of a cylindrical tank. The exhaust air is forced to flow upwardly as it first contacts the bottom of a carbon based filter media. The exhaust air then percolates through the carbon media in the tank until it is discharged out the top of the tank. As the exhaust air percolates through the media, the unwanted contaminants and odorous compounds are removed. The limitations of this common system is caused by absorption capacity of the carbon media which is directly related to the surface area of the media perpendicular to the flow of the exhaust air and the thickness of the media in the direction of the flow of the exhaust air. The surface area of the media is limited by the overall size of the system. In addition, the larger the surface area, the larger the media, thus the more expensive the media. The thickness of the media is limited by the pressure required to push the exhaust air through it. In essence, the thicker the media, the larger the blower required to push the exhaust air and more power to maintain the desired flow rate. Therefore, the larger the surface area and thickness of the media, the larger the overall system. For high flow rates, the large footprint of the system can be prohibitory. Additionally, the larger the footprint of the system, the higher cost for material, labor, and space required for the installation.
Accordingly, a more efficient carbon scrubber is desired that would permit larger volumes of exhaust air to be treated in a smaller footprint. In addition, easy access into the scrubber will allow quick and easy replacement of the spent carbon and filter media.